<style>
  #env-notice {
    position: fixed;
    left: 50%;
    top: 40%;
    z-index:100;
    width: 200px;
    margin-left: -100px;
    text-align: center;
  }

  #env-notice h2 {
    font-size: 50px;
    color: green;
    opacity: 0.2;
  }
</style>

<div id="env-notice" onclick="$('#env-notice').remove()">
  <h2><%= Rails.env == 'staging' ? '测试' : '开发' %>环境</h2>
</div>
